IL-6

Alias: Interleukin-6, B-cell hybridoma growth factor, Hybridoma growth factor

IL-6 pleiotropic TH2 cytokine produced by a variety of cell types that include monocytes, fibroblasts, and endothelial cells. Upon stimulation, IL-6 is secreted by many additional cell types including macrophages, T cells, B cells, mast cells, glial cells, eosinophils, keratinocytes, and granulocytes. IL-6 influences antigen-specific immune responses, inflammatory responses, it is a major mediator of the acute phase reaction and hematopoiesis, and plays a central role in host defense mechanisms. Furthermore, IL-6 is involved in B-cell differentiation, the induction of acute phase proteins in liver cells, growth promotion of myeloma/plasmacytoma/hybridoma cells, induction of IL-2 and IL-2R (CD25) expression, proliferation and differentiation of T cells, inhibition of cell growth of certain myeloid leukemic cell lines, and induction of their differentiation to macrophages. The level of IL-6 has proven to be a very important biomarker. This includes proliferative diseases where elevated plasma levels of IL-6 are observed in patients with multiple myeloma, other B-cell dyscrasias, Lennert’s T lymphoma, Castleman’s disease, renal cell carcinoma, and various other solid tumors. It is also an important biomarker in monitoring inflammatory responses were IL-6 is involved in the induction of acute phase proteins and induction of fever. Elevated serum levels of IL-6 are also found in patients with inflammatory arthritis and traumatic arthritis.